Internal combustion engine



Jan. 18, 1938.

w. s. B URN 2,105,717

INTERNAL COMBUSTION ENGINE Filed Nov. 13. 1935 tastes ass. is, rss

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2,14%,715 EENAL CQMBUSTION ENGINE Walter Scott Burn, Hartlepool, England, assignor to The National Gas and Oil Engine Company- Limited, Alfred Bickerton Balmford, Ashtonunder-Lyne,England, and Walter Scott Burn,

Hartlepool, England Application November 13, 1935, Serial No. 49,632- In Great Britain November 18, 1934 60laims.

or enable better results to be obtained than has heretofore been possible, particularly in single .acting two stroke oil engines. This is achieved by a cylinder exhaust system consisting of two 5 complete or approximately complete circumferential rows of ports, 1. e. an upper row which is used for admission of scavenging air juxtaposed to a lower row of exhaust ports.

The exhaust or lower ports are arranged to permit the easiest possible flow of gas to the exhaust belt and exhaust main which is located at one side of the cylinder, although said exhaust ports occupy the full circumferential width available; as The upper row of ports for admitting the scavenging air are the terminations of nozzle ports which are inclined upwards toward the combustion end of the cylinder but with a tangential component. A suitable valve, operated mechani(| ically or automatically, shuts ofi the scavenge air ports from the air supply until the exhaust ports have been opened by the piston and the pressure within the cylinder is reduced to below that of the appertaining scavenge allv pressure. The

35 valve then opens and air is admitted until the exhaust products are expelled and in addition a predetermined amount of supercharge air is forced into the cylinder.

The manner in which the invention can be carl0 ried into effect will be more readily understood from the description now about to be given with the aid of the accompanying drawing, in which Figs. 1, 2, 8, and 4 are diagrammatic views of a cylinder, piston and air control valve, each with $5 the partsin a different position. Fig. 5 is a horizontal diagrammatic section taken at the exhaust belt of Fig. 1, and Fig. 6 is a similar section taken at the scavenge air belt of Fig. 2. Fig. '7

is a diagram illustrating the conditions in the 50 cylinder at the end of the compression stroke.

In the figures, the ports for admission of scavenging and supercharging air are represented at l, and the exhaust ports at 2. The ports I are inclined upwardly, from an air belt 3, towards 55 the combustion end i of the cylinder as shown in Figs. 1 to 4, and at the same time tangentially as shown in Fig. 6. A valve controlling admission of air to the belt 3 is represented diagrammatically at 5, the same operating mechanically or automatically in practice. The exhaust ports 6 2 are similarly inclined toward the combustion end of the cylinder, but instead 01' being all inclined in one sense tangentially, they are divided into two sets, one set being inclined tangentially in a sense opposite to that or the other as shown 10 in Fig. 5.

Fig. 1 indicates by arrows the exhaust gas leaving the cylinder as the descendng piston uncovers the exhaust ports, the scavenge air admission valve 5 being closed. Fig. 2 similarly indicates the conditions which exist a little later when the piston has descended further and the valve 5 I advantage features:

First, a definite stability of action. That is, the air jets issuing from the ports I are not only highly developed from a nozzle port point of view to give a concentrated directioned flow, but shortly after leaving the ports the scavenge air streams as shown in Figs. 2 and 6 are made to impinge diagonally onto the cylinder walls, 1. e. they are to strike the cylinder walls substantially tangentially, circumferentially and with an inclination axially in such manner that a definite .guiding eii'ect is given to the air streams by the cylinder walls and consequently the air streams flow in helical paths very similarly to that of a multithreaded screw. The centrifugal or swirling effect of the rotating air, with its higher density 40 relative to the cylinder contents of exhaust gases, definitely tends to localize the scavenging action, the air tending to remain outwards adjacent the cylinder walls with its movement oi rotation and translation, thus causing the exhaust gas to be expelled down the centre'of the cylinder by displacement, this latter being represented by the arrows at (see Fig. 2). In other words, the general air and gas movement is upwards at the cylinder sides and downwards at the cylinder centre.

Second, the inside top of the cylinder, or the bottom of its cover, is made to present a shape represented by the curve 1 (see Fig. 1) such as $9 a d. reversal of the air flow after it has reached covered and uncoveredby the same piston working in the cylinder; the scavenging air ports bethe combustion space end of the cylinder, the tendency also being, as represented by the ar rows .12 (see Fig. 3) for the conical angle of the exhaust gas beneath the air streams to increase or flatten out after the air has reached the combustion end of the cylinder until the exhaust gas is expelled and the engine cylinder is filled with fresh rotating air. 7 1

Third, as the scavenge air ports -I are in process of being cut of! by the piston, (see Fig. 4),.the vertical or axialcomponent of the air stream near to the cylinder walls increases and the up and down action increases, thereby tending to create a vortex ring during the compression stroke, which is a favourable form 01' organized air movement 61' port,lwh.ich in the case of the exhaust ports 2 is particularly important to get the maximum of useful expansion and compression stroke.

Finally, from both the point of view of obtaining a maximurn'of initial air charge with a minimum of scavenging air, and also having the maximum of expansionlstroke', the described disposi-.

2 is decidedly advantageous. V

What I claim is:--

tion of the scavenge ports above the exhaust ports 1. An internal combustion engine cylinder having a complete circumferential row of ports for admission of scavenging air and ajuxtaposed circumferential rowofexhaust ports more re-.'

mote from the combustion end of the cylinder, both of said rows of ports being adapted to be ing the termination of nozzles-which are in-' clined toward the combustion end of the cylinder and having a tangential component with respect thereto. 2. An internal combustion engine cylinder having two approximately complete circumferential rows of ports one below the other, the upper 01' said two rows being for the admission of scaveng ing air and the lower of said rows being for the expulsion of exhaust gas, together witha valve controlling the admission of scavenging air through the first named, row and allowing such admission only after the second named row has been opened to exhaust. by piston movement opening and closing both rows; the said upper scavenging .air ports being terminals of nozzles extending through the walls'of the cylinder with inclination toward the combustion end thereof and having a tangential component with relation thereto.

3. An internal combustion engine cylinder having a complete circumferential rowof ports for the admission of scavenging air, a juxtaposed complete circumferential row of exhaust ports more remote from'the combustion end of the named row; the scavenging air ports being terminals of nozzles which are inclined toward the combustion end of the cylinder with a tangential component with relation thereto. and said valve controlling the supply oi scavenging air to admit it only when the row of exhaust ports have been uncovered by the piston so that the pressure within the cylinder is reduced below that of the scavenge air supply.

4. An internal combustion engine comprising a cylinder having two separate and complete-circumferential rows of ports at different levels below the top and an inner topshaped to present an approximately double concave surface to the combustion space, the upper row of ports nearer to the cylinder top being tangentially and upwardly inclined so as to cause entering air streams to. how uniformly upward and around in helical paths against the inner wall of the cylinder toward the top and the inner top surfacing causing it to then reverse and flow downward again centrally of the cylinder inside the area 01' initial flow of the entering air streams, thereby stabilizing the flow oi the scavenging air and permitting the same ports to be utilized for supercharging, and a valve controlling the air entry through said upper ports by a timing arrangement opening the same to air admission only after the lower row has been opened to gas exhaust; the said lower row of ports being also upwardly and somewhat tangentially inclined to the cylinder axis.

5. In an internal combustion engine, a cylinder having a circumferential row of exhaust ports below the top level, a circumferential row of scavenging air admission ports above the level of the exhaust ports; both of said rows of ports being opened and closed by piston movement, and a valve controlling the air admission ports operated in timed relation to the piston so as to admit scavenging air through said ports only after the exhaust ports therebelow have begun to. open and shutting oil the air supply again only after said exhaust ports have been again closedr the said air admission ports being terminals of nozzles extending through the cylinder walls from a surrounding belt chamber with an inclination toward the combustion end 01 the same and having a tangentialcomponent with relation thereto.

6. In an internal combustion engine, a cylinder having exhaust ports formed in a circumferential row below its top with an upward inchnation, a similarly formed upward and also mission ports above the level 01' the exhaust ports adapted to inject air streams into the combustion space with a helical swirling motion against the cylinder walls. toward its top, a top formed so as to reverse the swirling movement of injected air centrally downward through the space inside the entering streams to the lower exhaust port level, a piston formed with a conical top and operating to open and close both the exhaust and air admission ports, and a valve controlling said air admission ports to admit said air only when the exhaust ports have begun to open by the piston movement and to shut off said admission only when said exhaust ports have been again closed by the piston.

WALTER SCOT! BURN.

, tangentially disposed series of scavenging air ad- 

